Catheter

ABSTRACT

A catheter for epidural anesthesia comprising a plastic tube which has its near end open permitting adaptation to the tip of syringe or the like, and the opposite or distal end rounded and carrying embedded in the interior of same a metallic piece opaque to X-rays; having in the distal end, which is closed, from two to six longitudinal slits, each of which is both longitudinally and circumferentially offset from the nearest adjacent slit so that the diametral planes in which said slits are placed form a dihedral angle of at least 45*, and furthermore by the fact that none of the diametral planes in which each slit is located has more than one slit, thus affording the catheter practically the same rigidity as that of a catheter having no slit whatever.

United States Patent [1 1 Cami [451 May 27, 1975 i 1 CATHETER [22]Filed: Aug. 12, 1974 [21] Appl. No.: 496,690

Related US. Application Data [63] Continuation-impart of Ser. No.312,236, Dec. 4,

1972, abandoned.

[52] US. Cl 128/214; 128/2 R; 128/348 R; 128/350 V [51] Int. Cl... A6lm5/00; A6lb 25/00; A6lb 27/00 [58] Field of Search 128/214, 2 R, 2 B,130, 128/224, 348, 349 R, 349 B, 349 BV, 350 R, 350 V [56] ReferencesCited UNITED STATES PATENTS 2,969,066 1/1961 Holteret al 128/350 v3,020,913 2/1962 Heyer 128/350 V 3,086,525 4/1963 Whitcomb 128/2323,483,859 12/1969 Pittman 128/2 R 3,485,234 12/1969 Stevens 128/348 XSheridan 128/348 Dalton 128/2 R Primary Examiner-Aldrich F. MedberyAttorney, Agent, or Firm-Ladas, Parry, Von Gehr, Goldsmith & Deschamps[57] ABSTRACT A catheter for epidural anesthesia comprising a plastictube which has its near end open permitting adaptation to the tip ofsyringe or the like, and the opposite or distal end rounded and carryingembedded in the interior of same a metallic piece opaque to X-rays;having in the distal end, which is closed, from two to six longitudinalslits, each of which is both longitudinally and circumferentially offsetfrom the nearest adjacent slit so that the diametral planes in whichsaid slits are placed form a dihedral angle of at least 45, andfurthermore by the fact that none of the diametral planes in which eachslit is located has more than one slit, thus affording the catheterpractically the same rigidity as that of a catheter having no slitwhatever.

3 Claims, 3 Drawing Figures CATHETER CROSS REFERENCE TO RELATEDAPPLICATIONS This application is a continuation-in part of my copendingapplication Ser. No. 312,236, filed Dec. 4, I972, and now abandoned, forCatheter.

BACKGROUND OF THE INVENTION In recent years the technique ofadministering anesthetics in liquid form directly into the spinalcolumn, specifically into the peridural space, has been improved,achieving benefits in comparison to general anesthesia of the patient,and particularly to that accomplished be means of anesthetic gases, incases of sur' gery particularly of the lower abdomen and the legs,because the sensibility of the patient is successfully isolated in theseareas without loss of consciousness, and without saturating the bloodstream with anesthetic solutions.

Epidural anesthesia has also proved advantageous in childbirth, whetheror not controlled by the introduction of ocitosics.

To administer this anesthesia it was at first necessary to insert aspecial needle into the resistant external tissues, between thevertebrae and through the softer and extremely delicate internal tissuesbefore achieving penetration into the epidural space.

At first the anesthetic was administered directly through the needle,with the corresponding danger which a sharp pointed instrument of thischaracter represents in such a critical spot.

Later on it became preferable to effect the operation by means ofintroducing a flexible tube of thermoplastic material of a diameterwhich could be passed through the inside of the needle which had been inserted into the body by direct puncture or by incision, permittingthereafter the extraction of the needle sliding over the tube when thelatter had been placed in the desired location; this is tested byextracting through the tube a biological liquid sample. The tube of thefirst catheter had both ends cut square, and on one end it included asmall adapter so that once the needle was withdrawn, a syringe withanesthetic could be attached.

Notwithstanding the advantages of the flexible catheter with square cutends, over the administration of anesthetics by a simple needle, theedges of the square cut of the tube produce trauma in the delicatetissues through which the catheter passes and cause postoperatory painto the patient; in addition, since the said catheter has no penetrationmarkings, it is difficult to know to what depth the tube had beeninserted.

Furthermore, with this tube the exact location of same in the epiduralspace is unknown, since the thermoplastic material of which it is madecannot be detected with X-rays.

Another problem caused by this catheter with square cut ends is that theorifice in the end of the tube frequently becomes blocked, since it isprecisely the end, thereof that is used to achieve penetration, andhence in the opening of the tube tiny clots, fibers and particles of thetissue itself are deposited, obstructing the passage of the anestheticliquid.

Subsequently, in order to avoid the foregoing problems, a catheter wasdeveloped which had the penetration tip at its distal end rounded to abullet shape to reduce the trauma of adjacent tissues and to facilitatepenetration through them.

The orifices for supplying the anesthetic in said catheter consisted oftwo practically circular lateral apertures near the distal end,diametrically opposite each other, and slightlyseparated from each otherin respect to the lengthwise axis of the catheter.

Furthermore, in this catheter or probe indelible markings were providedseparated by a certain interval, with the object of determining thepenetration of the catheter.

Notwithstanding the progress achieved with this catheter, the shape andlocation of the lateral orifices seriously affected the strength of thetube, and weakened it, since the catheter in its penetration travelgenerally bends principally at the said orifices, causing seriouscomplications such as the obstruction of the flow of the anestheticliquid, difficulty in the withdrawal of the catheter when the bend isvery pronounced, and occasionally the tip of the catheter comes off;obviously it is more difficult to accomplish penetration of the catheterunder such conditions.

In addition to the problems mentioned with each of the cathetersindividually cited, they all uniformly have the drawback that, sincewithin the epidural space there is a higher pressure than atmosphericpressure, the cephalorachidian liquid tends to escape through thecatheter in cases where accidentally or intentionally the syringe isdisconnected from the adapter or the latter from the catheter, thusproducing a loss of the cited liquid with corresponding serious results.

In some catheters, in order to determine their position within the humanbody, heavy metals have been mixed with the plastic material; while thisdoes produce a certain opacity which can be detected by X-rays, it isnot very precise, since the epidural space into which the catheter is topenetrate is surrounded by bone tissue.

The above references are the best known in the field of catheters forepidural anesthesia; however, outside of this field, and for the solepurpose of differentiating them from the present invention, drain tubesor shunts operating on differential pressure may be mentioned; they areplaced in the body permanently or for prolonged periods; some of themare for draining cerebrospinal fluid to either the atrium or theperitoneum. Since the pressure in the atrium is greater than thepressure in the cerebroventricular space, the drain tube has beenprovided with valving cuts at one of its ends, so as to prevent theback-flow of blood toward the ventricle; at its other end the drain tubehas circular perforations; some of these tubes have as a backing memberan inner concentric cylindrical body near the cuts to prevent the latterfrom becoming blocked; the arrangement of the cuts has not been made inthese shunts specifically to give the tube strength, and furthermore,one of their ends generally carries circular perforations. Obviously,both the structural elements of these pressure shunts and theirapplication are outside of the field of catheters for supplying epiduralanesthesia of the present invention.

SUMMARY OF THE INVENTION In view of the foregoing it is one object ofthe present invention to provide a catheter for epidural anesthesiawhich has its distal end rounded to prevent damage to the adjacenttissues during its penetration, thereof, and

which has embedded in the material of this distal end a piece of wirewhich is inert to biological tissue, which does not effect an ioninterchange with biological fluids or tissue, and which may be stainlesssteel, with a low content of carbon, gold, platinum, alloys of cobalt,chrome and molybdenum, etc, and which is clearly detectable by X-rayseven when the catheter is surrounded by bone tissue; and havingpenetration interval markings which will allow the user to determine theexact location of its application,

Another object of this invention is to provide a catheter having nearits distal end a plurality of longitudinal radial slits to dispense theanesthetic which open only when a syringe or the like attached to thenear end of the catheter develops a greater positive pressure than thatprevailing in the cavity in which the anesthetic is to be delivered, orotherwise, when the syringe exerts a negative pressure or suction suchthat the slits open permitting the withdrawal of a sample of thebiological liquid in order to determine the location of the catheter.

Each one of said radial slits is both longitudinally andcircunferentially offset from the nearest slit so that no singlediametral plane has more than one slit and the dihedral angle betweendiametral planes carrying adjacent slits is at least 45, whereby thecatheter is given the same rigidity as if it had no slits, enabling itto make easy penetration without the problems aforementioned due tobending of same.

These and other objects to be obtained through the use of this inventionwill be better understood and more fully perceived in the followingdescription which refers to the attached drawings of the preferredembodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, is an elevational view showingthe catheter of the present invention cut into sections and attached toan adapter at its near end, which is in turn coupled to the tip of ahypodermic syringe.

FIG. 2, is a detail view of the distal end of the catheter of thepresent invention, showing the longitudinal slits to deliver anesthetic,disposed in different diametral planes and in a conventional sectionshowing the piece of metallic wire embedded in the inside of the distalend, which is easily detectable with X-rays.

FIG. 3, is a cross-sectional view along 3-3 of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION The improved catheter 11 of thepresent invention, is composed of a tube 12 of thermoplastic materialhaving a rounded distal end 13, bullet shaped to facilitate itspenetration through adjacent tissues until it reaches the epiduralspace, and having its near end 14 so made as to permit the attachementof an adapter 15 which in turn can be attached to a hypodermic syringe16 partially shown, by means of which a positive pressure is applied tothe anesthetic contained therein, causing it to pass through the lengthof tube 12 and discharging it in the epidural space through certainlongitudinal slits 17 placed radially in relation to the longitudinalaxis of tube 12 and so disposed in diametral planes that the dihedralangle formed between the diametral planes of two adjacent slits is atleast 45 and that furthermore, none of the said diametral planescontains more than a single slit 17, thus giving the catheter the samerigidity as if it had no slit whatever, to permit its ready penetrationwithout the danger of bending or breaking.

The catheter 11 of the present invention further has embedded in thedistal end 13, thereof as shown in FIG. 2 a piece of metallic wire 18which is inert to biological tissues and which does not engage in ionexchange with the biological liquids and tissues, being of such amaterial as stainless steel with low content of carbon, platinum, gold.alloys of cobalt, chrome and molybdenum, etc., said metallic portion 18being readily detectable by means of X-rays even when catheter 11 issurrounded by bone tissue, as is usual in cases of epidural anesthesia.

The tube 12 also includes markings 19, 20, 21, which are different fromone onother and spaced along the catheter to show the person applyingthe anesthesia the location and penetration of the catheter and of theslits for delivering anesthetic. This indication can be further mademore precise by means of X-rays, thereby detecting the position ofmetallic portion 18.

Once the slots 17 for delivering anesthetic are in the intended epiduralspace a negative pressure is applied with the syringe 16 withdrawing asample of the biological liquid and when the source of the latter hasbeen determined a positive pressure is applied upon the anesthetic,delivering it through slits 17 into the epidural space.

The initial penetration of the catheter 11 is carried out as describedat the beginning by passing it slidingly through a hypodermic needle,which is done by marking a prior incision or puncture in the externaltissues of the patient, and later withdrawing this placement needle oncethe catheter 11 has been situated in the desired location.

It is important to note that the opening of slits 17, is effected solelyby the application of a positive or negative pressure, thus preventingthe back-flow of fluid through a mere pressure difference due tocarelessness with the resulting complications and problems.

While, the foregoing description has been drawn to a specific embodimentof the invention, it will be understood by all those skilled in thesubject matter that changes in form and detail are encompassed withingthe scope and spirit of the invention.

I claim:

1. A catheter for epidural anesthesia composed of a plastic materialhaving its near end open and adapted for connection to a syringe andhaving its distal end closed androunded and having embedded in itsinternal portion a metallic piece which is opaque to X-rays, saidcatheter having near its distal end a plurality of longitudinal slitsfor delivering anesthetic, each of said slits being both longitudinallyand circunferentially offset from the nearest slit so that each slit beplaced in a different diametral plane, and being so spaced from theadjacent slit that the diametral planes on which they are located forman angle of at least 45, thus giving the catheter substantially equalrigidity to that of a catheter having no slit whatever.

2. The catheter for epidural anesthesia as described in claim 1, whereinthe slits for delivering anestesic consist of from two to six slitslongitudinally spaced from each other.

3. The catheter for epidural anesthesia as described in claim 1, whereinthe metallic portion for detection by X-rays embedded within the distalend of the catheter is a piece of cylindrical wire which is inert tobiological tissues and does not engage in ion exchange with thebiological liquids and tissues.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,885,561 Dated May 27, 1975 I Charles N. MAZAL-CAMI It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

On the cover sheet, left column, the inventor s last name "Mazal Cami"should read-- Mazal-Cami.

On the cover sheet, left column, below "[21] Appl. No.: 496,690" shouldbe added [30] Foreign Application Priority Data December 15, 1971 Mexico..l32,l27.

Signed and gcaled this twenty-third D 3)! Of September I 975 [SEAL]Arrest:

RUTH C. MASON C. MARSHALL DANN .-lrt(sling ()ffiver (nmmmsimu'rnj'larcnls and Trademarks

1. A catheter for epidural anesthesia composed of a plastic materialhaving its near end open and adapted for connection to a syringe andhaving its distal end closed and rounded and having embedded in itsinternal portion a metallic piece which is opaque to X-rays, saidcatheter having near its distal end a plurality of longitudinal slitsfor delivering anesthetic, each of said slits being both longitudinallyand circunferentially offset from the nearest slit so that each slit beplaced in a different diametral plane, and being so spaced from theadjacent slit that the diametral planes on which they are located forman angle of at least 45*, thus giving the catheter substantially equalrigidity to that of a catheter having no slit whatever.
 2. The catheterfor epidural anesthesia as described in claim 1, wherein the slits fordelivering anestesic consist of from two to six slits longitudinallyspaced from each other.
 3. The catheter for epidural anesthesia asdescribed in claim 1, wherein the metallic portion for detection byX-rays embedded within the distal end of the catheter is a piece ofcylindrical wire which is inert to biological tissues and does notengage in ion exchange with the biological liquids and tissues.